1. Technical Field
This invention relates generally to densitometers for electrophotographic apparatus such as electrophotographic reproduction apparatus.
2. Background Art
Electrophotographic apparatus that have film belt photoconductors commonly have transmission densitometers which shine IR radiation through a toned test patch and the belt, to be detected on the other side of the belt. The detected signal is linear with respect to the mass of toner on the patch.
Electrophotographic apparatus that have drum-type photoconductors must resort to reflection densitometers because IR radiation does not pass through the drum. Reflection densitometers are inferior to transmission densitometers because the signals generated by the former are not linear with respect to the toner mass, at least at the high densities.